Nepenthes pitcher plants are unusual in many ways. They are carnivorous. They use a radically transformed leaf blade as a pitcher to trap insects. They also have evolved a biomechanical ridge system on the pitcher’s rim that is unusually wettable and slippery. The cells forming this rim point inward, towards the pitcher interior, forcing the insect to slip inside where it is trapped and consumed. A recent study published in Annals of Botany by Lessware et al has now provided the first account of the developmental timeline for this complex trapping surface.
To identify the pattern of development, Lessware et al defined seven consecutive development stages in N. × hookeriana pitchers and prepared a time-series of cryo-scanning electron microscopic images (cryo-SEM), a method that enables researchers to quickly handle and fix delicate material under cryogenic conditions.
“We sampled 30 pitcher buds representing the entire developmental timeline from the bud orientation stage through to the mature, freshly open trap,” they explain. Their imaging showed that the developmental patterning of the epidermal cells in pitcher rims is similar to that seen during leaf and flower development, namely proliferation, differentiation and then expansion. The only thing unusual was that the cells went through repeated divisions without intermittent growth, leading to a reduction in average cell size not normally seen during organ development of other species.
“We show that the hierarchical surface pattern on the mature peristome [rim] is formed through a sequence of differentiation and growth events that combine modular elements which are common and widespread in epidermal development across plant lineages and organs, where they are underpinned by homologous genes with robust function,” say Lessware et al.
The cryo-SEM images were also used to build an identification key that can infer the internal rim developmental stage from external pitcher bud morphology. The key was validated by sampling 56 buds, analysing their external development by standard SEM and checking the prediction. The key had over 95% predictive accuracy, with all the incorrect predictions from young buds early in development. Additionally, the key is specific to lower type pitchers.
According to Lessware et al, the slippery rim of the pitcher plant has “provided inspiration for biomimetic applications such as self-cleaning, self-healing surface coatings and microfluidic devices for passive unidirectional water transport and fog harvesting” and may “offer an innovative solution to environmentally friendly pest control.”
“Most leaf surfaces are water-repellent,” say Lessware et al, but “the collar-shaped, micro-textured trap rim (peristome) of carnivorous Nepenthes (Nepenthaceae) pitcher plants is a remarkable exception to this rule.” This specialized rim of the pitcher plant has an intricate ridge pattern that guides water along its surface to form a thin film. “The water film prevents the adhesive footpads of insects from making close contact with the surface and causes them to slip, like a car tyre aquaplaning on a wet road,” say Lessware et al. By better understanding how the slippery surface is created in Nepenthes, it may be possible learn how to make plant surfaces too slippery for insects to infest them.
And with the establishment of a developmental timeline for rim epidermal cells, the door is open to better understanding the genetics behind this complex slippery trait.
READ THE ARTICLE
Lessware, O.C., Mantell, J.M. and Bauer, U. (2025) “Carnivorous Nepenthes pitcher plants combine common developmental processes to make a complex epidermal trapping surface,” Annals of Botany, 135(4), pp. 643–654. Available at: https://doi.org/10.1093/aob/mcae147.
See also
Whitewoods, C.D. (2025) “Rearranging development makes a slippery slope: a commentary on ‘Carnivorous Nepenthes pitcher plants combine common developmental processes to make a complex epidermal trapping surface,’” Annals of Botany, 135(4), pp. i–ii. Available at: https://doi.org/10.1093/aob/mcae182.
Cover image: Nepenthes × hookeriana Canva.
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